Washington State is in the top 25, Arizona is a couple spots ahead of Utah -- so that's why they have a higher chance of winning.
FPI shouldn't be taken as a true ranking or even a power ranking. It just projects wins and losses using recruiting and strength of schedule among other variables. It's usually fairly accurate when showing which teams are better than others, but it doesn't predict every game 100%.
http://www.espn.com/college-football/statistics/teamratings